Colored and white light generating lighting device

Abstract

A lighting device for generating colored and white light. According to the invention the lighting device comprises at least one light source ( 1, 4 ) emitting blue or ultraviolet light and a color conversion unit ( 2, 5 ) for converting said blue or ultraviolet light into visible light comprising at least two sections ( 2 a, 2 b, 2 c, 6 a, 6 b, 6 c, 6 d ), at least one section ( 2 c, 6 d ) of which being a transparent or translucent color converting section, said color conversion unit ( 2, 5 ) being arranged for alternately illuminating said at least two sections ( 2 a, 2 b, 2 c, 6 a, 6 b, 6 c, 6 d ) with said blue or ultraviolet light, said at least one color converting section containing luminescent material, wherein said luminescent material is a luminescent organic dye in a polymer matrix or a crystalline inorganic luminescent material.

The invention claimed is: 
     
       1. Lighting device for generating colored and white light, comprising:
 at least one light source emitting blue or ultraviolet light, 
 a color conversion unit for converting said blue or ultraviolet light into visible light comprising at least two sections, at least one section of which being a color converting section, said color conversion unit being arranged for alternately illuminating said at least two sections with said blue or ultraviolet light, said at least one color converting section containing luminescent material, 
 wherein said luminescent material is a crystalline inorganic luminescent material formed into a ceramic body, and wherein said luminescent material avoids beam deflection of light incident on the luminescent material and is substantially non-scattering, and 
 wherein said inorganic luminescent material exhibits a density of more than 97% of its theoretical density as a single crystal material. 
 
     
     
       2. The lighting device of  claim 1 , wherein said light source is a light emitting diode. 
     
     
       3. The lighting device as claimed in  claim 1 , wherein said color converting section is arranged to convert said blue or ultraviolet light into green light and contains SrSi 2 O 2 N 2 :Eu and/or LuAG:Ce as the crystalline inorganic luminescent material or wherein said color converting section is arranged to convert said blue or ultraviolet light into red light and contains CaS:Eu and/or CaAlSiN 3 :Eu as the crystalline inorganic luminescent material. 
     
     
       4. The lighting device as claimed in  claim 1 , wherein said color conversion unit is designed as a rotational oscillator to be rotated with a rotational frequency or linear oscillator to be oscillated with an oscillation frequency. 
     
     
       5. The lighting device of  claim 4 , wherein said rotational oscillator is a color wheel to be rotated with a rotational frequency comprising at least two sectoral sections, at least one of which being a transparent or translucent color converting section. 
     
     
       6. The lighting device of  claim 5 , wherein said color wheel comprises at least four sections to perform more than one color cycle per revolution. 
     
     
       7. The lighting device of  claim 5 , wherein the contact surfaces between said sectoral sections are provided with a reflective coating. 
     
     
       8. The lighting device of  claim 4 , wherein said linear oscillator comprises a piezo actuator or a solenoid. 
     
     
       9. The lighting device as claimed in  claim 1 , wherein said light source is a pulsed light source and the lighting device further comprises a electronic control unit arranged to synchronize the pulse pattern of said pulsed light source with the alternating frequency of said color conversion unit so as to generate the desired shade of color. 
     
     
       10. A method for generating colored and white light, comprising
 at least one light source emitting blue or ultraviolet light, 
 providing a color conversion unit for converting said blue or ultraviolet light into visible light, said color conversion unit comprising at least two sections, at least one section of which being a color converting section, said at least one color converting section containing luminescent material, said luminescent material being a luminescent organic dye in a polymer matrix or a crystalline inorganic luminescent material formed into a ceramic body, said luminescent material being configured to avoid beam deflection of light incident on the luminescent material and to be substantially non-scattering, and alternately illuminating said at least two sections with said blue or ultraviolet light, and 
 wherein said inorganic luminescent material exhibits a density of more than 97% of its theoretical density as a single crystal material. 
 
     
     
       11. The method of  claim 10 , wherein the light source is a pulsed light source and the pulse pattern of said pulsed light source is synchronized with the alternating frequency of said color conversion unit so as to generate the desired shade of color. 
     
     
       12. The lighting device of  claim 1 , wherein the color converting section partly transmits light emitted by the light source. 
     
     
       13. The lighting device of  claim 1 , wherein the luminescent material is transparent.